Building a Home Security System with Raspberry Pi: Build your own sophisticated modular home security system using the popular Raspberry Pi board

The baby of the family is the Model A; it was released as a lower-cost version of the Model B, shown in the following section. Its main differences from the Model B are that it features just 256Mb of memory and has no Ethernet port; so if you want to connect this board to a network, you are limited to using a USB Wi-Fi dongle.

The Raspberry Pi Model A Board Layout

This was the first version of Raspberry Pi to be released; an updated revision, which improved the power system and USB port protection, came later. It features 512Mb of memory and has an Ethernet port for connecting to your network. This is probably the most common version used, and having the Ethernet port is incredibly useful, especially to get up and run quickly in order to set up and configure your Pi without the need for a keyboard and monitor.

The Raspberry Pi Model B Layout

In 2014, the Raspberry Pi Foundation released a new version of the board that had some fundamental changes as compared to the previous version. The most fundamental changes were the board layout, form factor, and mounting points—much to the dismay of the many enclosure and accessory manufacturers out there.

In fact, we were in the middle of prototyping an enclosure for a commercial product that we were developing based on the Raspberry Pi—fortunately we caught wind of the board change in the nick of time and were able to change our enclosure to support the upcoming model B+.

The main electronic changes to this board are the addition of 2 more USB ports that can deliver more power to peripherals, an expanded GPIO interface, and the removal of the composite video port that is now consolidated into the audio jack. It also now uses a micro SD card with a better card slot.

In February 2015, a more powerful Raspberry Pi was released: the Raspberry Pi Model 2. It's similar to the Model B+ in terms of form-factor and interfaces, but is now reportedly 6-times faster than the Model B/B+ with its upgraded ARM processor and 1Gb of memory.

At the same low cost of less than £30, it's a fantastic little board and a great power-house for embedded systems.

The Raspberry Pi Model B+ and Model 2 Layout

Essentially, any version of the Raspberry Pi will work with the modules presented in this book, but if you want to exploit features such as the camera, which may require more processing power and memory, or want to have an Ethernet connection, you'll need to use the Model B.

If you want to start plugging additional stuff into the USB port, such as a GSM modem, then I recommend that you use the Model B+ as it delivers more power to those kinds of devices without the need for additional USB hubs.

If you want to do more processing with video and images from an attached camera, or want to connect lots of things, then go for the latest Model 2 board. I'm going to assume that's the one you have chosen for this project, and that's the one I'll be using throughout this book; just be aware of any limitations if you choose to use an earlier model.

You'll need to grab the latest Raspbian OS image from the Raspberry Pi site at https://www.raspberrypi.org/downloads.

Download the Raspbian OS ZIP file containing the image to your PC.

Once downloaded, unzip the file and you'll have the file, 2015-09-24-raspbian-jessie.img.

The next thing to do is burn this image to your SD card…

On a Windows PC, the best way to burn the image to your SD card is to use the Win32 Disk Imager utility. This can be downloaded from http://sourceforge.net/projects/win32diskimager.

It doesn't have an installer, and launches directly from the EXE file.

Now, it's time to create your SD card image:

On a Linux PC, you'll need to use the gparted and dd utilities to burn the image on your SD card.

Carry out the following steps to create your SD card image:

You're now ready to boot up your Raspberry Pi. Pop your shiny new SD card into it and plug in the power.

Assuming that you have a monitor attached to your Pi, you should see your system booting up nicely. Although you could wait for it to boot up and connect to it via a terminal session (we'll look at that later), I recommend that you connect a monitor to it, at least in the first instance, just to make sure everything is working correctly.

In the new Jessie version of Raspbian, you'll boot straight into a desktop GUI, which is a major change from previous versions, where you'd be taken to the raspi-config utility, the first time the system is run, where you'd set up your Pi, and importantly, expand the file system to use the entire space available on your SD card.

Debian Jessie boots into the GUI by default

When you first create your Raspbian SD card, you'll only be left with about 200Mb of space in the file system, regardless of the size of your SD card. This is not much use, so we want to expand the file system so that it uses all of the available space on the card.

Fortunately, this is very easy on the Raspberry Pi now, as this function is available in the Raspberry Pi Configuration Tool on the desktop.

To access the new configuration tool, go to Menu and select Preferences | Raspberry Pi Configuration.

The new Raspberry Pi Configuration Tool

Anyway, now we click on the Expand Filesystem button, and in a couple of seconds, you'll see a confirmation message. The filesystem will be expanded when the system next reboots.

Using the raspi-config utility

If you have an older version of Raspbian, or you're not using the desktop GUI, then you'll need to use the raspi-config utility (which is still better than the old days when we had to do this manually in the shell). The first time you boot up, you'll be taken straight to the raspi-config utility.

The first option is the Expand Filesystem option; select this and you'll see various commands scrolling up the screen. Once it's finished, you'll see the following message:

Root partition has been resized.
The filesystem will be enlarged upon the next reboot

Click on OK.

Select Finish on the config screen and reboot your Pi when prompted.

After your Pi reboots with its fuller file system, you'll be taken straight to the shell prompt where you can log in with the default user and password.

Login: pi

Password: raspberry

Something that you should get into the habit of doing is updating the operating system regularly; even though you may have the latest image installed, it's very likely that there are updated packages available. To update your OS, enter the following command:

$ sudo apt-get update

After this, enter the following one:

$ sudo apt-get dist-upgrade

This may take a while, depending on the number of updates required.

The Raspberry Pi doesn't have on-board real-time clock hardware. This is one of the deliberate omissions to keep the cost of the board down. Instead, the Pi gets its time when it boots up from time servers on the Internet using the Network Time Protocol (NTP). However, if there is no Internet connection at the time of booting up, then the time will be wrong.

$ sudo apt-get install fake-hwclock

$ cat /etc/fake-hwclock.data

$ service ntp stop
$ ntpd –gq
$ service ntp start

There's no point in having a security system if the system itself is not secure. So, now we'll change the default password for the pi user.

From the prompt, type the following command:

$ sudo passwd pi
pi@raspberrypi ~ $ sudo passwd pi
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully

$ sudo su

# passwd
root@raspberrypi:/home/pi# passwd
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully
root@raspberrypi:/home/pi#

You can also connect your Raspberry Pi to your network using Wi-Fi by plugging a USB dongle into it. There are additional configuration steps required to make this work, which are beyond the scope of this chapter, but there are many resources available covering this subject.